A method for efficiently recovering protein, lactic acid and potassium chloride in phytate-free corn soaking water

Abstract

The application discloses a method for efficiently recovering protein, lactic acid and potassium chloride in dephytinized corn soaking water, which comprises the following steps: filtering the dephytinized corn soaking water by using a ceramic membrane to collect permeate I; adding tartaric acid into the permeate I to adjust the pH, and performing cooling reaction to collect filtrate I; concentrating the filtrate I to obtain concentrated liquid I, and performing cooling crystallization on the concentrated liquid I to obtain filtrate II and filter cake II, wherein the filter cake II is dried to obtain lactic acid; diluting the filtrate II by adding water to obtain dilution liquid, performing electrodialysis treatment on the dilution liquid to collect dilution liquid and salt phase liquid; concentrating the dilution liquid to obtain concentrated liquid II, and drying the concentrated liquid II to obtain protein; concentrating the salt phase liquid to obtain concentrated liquid III, performing thermal concentration on the concentrated liquid III to obtain concentrated liquid IV, performing filtration on the concentrated liquid IV after decoloring treatment, and performing crystallization on the filtrate to obtain filtrate III and filter cake III, wherein the filter cake III is dried to obtain potassium chloride.

Description

Technical Field

[0001] This invention relates to the field of corn soaking water technology, specifically to a method for efficiently recovering protein, lactic acid, and potassium chloride from dephytate-treated corn soaking water. Background Technology

[0002] Corn soaking solution is a byproduct of corn processing and contains abundant phytic acid and inositol. Phytic acid is a naturally occurring organic acid found in plant seeds with strong chelating properties, capable of forming stable complexes with metal ions. Inositol is a water-soluble bioactive substance with various physiological functions, such as improving cell metabolism and lowering cholesterol. Therefore, corn soaking water is mainly used to produce phytic acid and inositol.

[0003] Currently, phytic acid in corn soaking water is mainly adsorbed by resin. This process generates a large amount of dephyticated corn soaking water, which also contains abundant water-soluble proteins, lactic acid, and salts. Therefore, it is of great significance to recover these substances from the solution.

[0004] Patent application number 202410688746.X discloses a method for preparing high-content protein and simultaneously producing salts using corn soaking water. Specifically, the method involves sequentially passing the filtered corn soaking water (after removing phytic acid) through an acidified ZG-6 resin and an alkalized ZG-312 resin for adsorption treatment. The effluent from the alkalized ZG-312 resin is then concentrated by evaporation, cooled for crystallization, and centrifuged. The supernatant is spray-dried to obtain protein powder, which is then centrifuged, precipitated, and dried to obtain lactate. The acidified ZG-6 resin is then eluted with hydrochloric acid solution, and the solvent is removed from the eluent to obtain inorganic salts. Finally, the alkalized ZG-312 resin is eluted with alkali solution, and the solvent is removed from the eluent to obtain metal salts. While this method recovers the protein, lactate, and metal salts from the phytic acid-free solution, the entire process uses a large amount of organic solvents, is complex, and increases costs. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for efficiently recovering protein, lactic acid and potassium chloride from dephytic corn soaking water, which addresses the shortcomings of the existing technology. This method recovers the effective components in dephytic corn soaking water under certain conditions, improves the economic value of dephytic corn soaking water, and is simple to operate and low in cost.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] A method for efficiently recovering protein, lactic acid, and potassium chloride from dephytate corn soaking water includes the following steps:

[0008] (1) Use a ceramic membrane to filter the corn soaking water to remove phytic acid and collect the permeate.

[0009] (2) Add tartaric acid to permeate solution one, adjust the pH of the solution to 5-5.5, cool down the reaction, filter the solution after the reaction is complete, and collect filtrate one;

[0010] (3) Concentrate the filtrate to obtain concentrated liquid one. Slowly cool the concentrated liquid one and crystallize it. Finally, filter the crystallized liquid to obtain filtrate two and filter cake two. Dry the filter cake two to obtain lactic acid.

[0011] (4) Add water to the second filtrate to dilute it and obtain a diluted solution. Perform electrodialysis on the diluted solution. Use a divalent ion separation membrane for electrodialysis. Treat until the conductivity of the solution in the desalination chamber is <8-9 ms / cm, then stop the operation and collect the desalination solution and the salt phase solution.

[0012] (5) Concentrate the desalination solution to obtain concentrated solution II, and finally dry it to obtain the protein product;

[0013] (6) The salt phase liquid is concentrated by reverse osmosis membrane to obtain concentrated liquid three. Concentrated liquid three is heated to obtain concentrated liquid four. Concentrated liquid four is decolorized and filtered while hot. The filtrate is cooled and crystallized. Then the crystallized liquid is filtered to obtain filtrate three and filter cake three. Filter cake three is dried to obtain potassium chloride. Filtrate three is combined into the next batch of salt phase liquid for processing.

[0014] Preferably, in step (1), the pore size of the ceramic membrane is 40-60 nm.

[0015] Preferably, in step (2), the tartaric acid is 0.5-1% of the volume of the permeate; and potassium hydroxide is used to adjust the pH of the permeate.

[0016] Preferably, in step (2), the cooling reaction process involves cooling the permeate to 20°C at a rate of 10°C / h and reacting for 2-4 hours.

[0017] Preferably, in step (3), the solid content of the concentrate is 58-63 wt%; the slow cooling process is to cool down to 25°C at a cooling rate of 10°C / h and crystallize for 12-24h.

[0018] Preferably, in step (4), the refractive index of the diluent is 20-30; during electrodialysis, water is added to the salt phase chamber and one of potassium sulfate solution and sodium sulfate solution is added to the electrode chamber, the concentration of the potassium sulfate solution and sodium sulfate solution is 3-5 wt%; the fixed current during electrodialysis is 3.3-3.5 A.

[0019] Preferably, in step (5), the solid content of concentrate II is 50-55 wt%.

[0020] Preferably, in step (6), the solid content of the concentrate three is 13wt%, and the membrane pressure during concentration is 5-6MPa; the solid content of the concentrate four is 60wt%.

[0021] Preferably, in step (6), activated carbon is added during the decolorization process. The amount of activated carbon added is 1-3‰ of four volumes of the concentrated liquid. The temperature of the decolorization process is 80℃ and the time is 2-3h.

[0022] Preferably, in step (6), during cooling crystallization, the filtrate after decolorization is cooled to 20°C at a rate of 10-15°C / h, and the crystallization process lasts for 12-20h.

[0023] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0024] 1. This invention uses a ceramic membrane to perform preliminary filtration and clarification of the water used to soak dephytic corn, removing impurities from the water and facilitating subsequent processing.

[0025] 2. This invention uses tartaric acid to remove calcium and magnesium ions from the solution. By controlling the amount of tartaric acid, reaction temperature, and pH of the solution, the calcium and magnesium ions in the solution are fully complexed and precipitated with tartaric acid. This ensures the stability of the electrodialysis process and improves the separation efficiency. It also facilitates the subsequent recovery of lactic acid from the solution.

[0026] 3. In order to recover lactic acid from the solution, the present invention concentrates the solution to a certain solid content before crystallization, and then controls the cooling rate of the concentrate, the crystallization temperature and the crystallization time to precipitate lactic acid, thereby obtaining a high content of lactic acid.

[0027] 4. This invention uses electrodialysis to separate the protein and potassium chloride components in the diluent. The electrodialysis membrane is a divalent ion separation membrane. Under certain conditions, the protein is enriched in the protein solution and the potassium chloride is enriched in the salt phase solution. The protein solution is subsequently concentrated and dried to recover the high content of protein. The salt phase solution is subsequently concentrated and crystallized to recover the high content of potassium chloride product.

[0028] 5. This invention uses dephyticated corn soaking water as raw material and combines technologies such as concentration, acid precipitation, and electrodialysis to effectively recover lactic acid, protein, and potassium chloride from the solution, thereby improving the economic value of dephyticated corn soaking water. Moreover, the entire process uses less organic solvent and generates less waste liquid, thus saving energy and reducing consumption. Detailed Implementation

[0029] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0030] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0031] To address the problems identified in the background section, the present invention discloses the following technical solution:

[0032] A method for efficiently recovering protein, lactic acid, and potassium chloride from dephytate corn soaking water includes the following steps:

[0033] (1) Use a ceramic membrane to filter the corn soaking water to remove phytic acid and collect the permeate.

[0034] (2) Add tartaric acid to permeate solution one, adjust the pH of the solution to 5-5.5, cool down the reaction, filter the solution after the reaction is complete, and collect filtrate one;

[0035] (3) Concentrate the filtrate to obtain concentrated liquid one. Slowly cool the concentrated liquid one and crystallize it. Finally, filter the crystallized liquid to obtain filtrate two and filter cake two. Dry the filter cake two to obtain lactic acid.

[0036] (4) Add water to the second filtrate to dilute it and obtain a diluted solution. Perform electrodialysis on the diluted solution. Use a divalent ion separation membrane for electrodialysis. Treat until the conductivity of the solution in the desalination chamber is <8-9 ms / cm, then stop the operation and collect the desalination solution and the salt phase solution.

[0037] (5) Concentrate the desalination solution to obtain concentrated solution II, and finally dry it to obtain the protein product;

[0038] (6) The salt phase liquid is concentrated by reverse osmosis membrane to obtain concentrated liquid three. Concentrated liquid three is heated to obtain concentrated liquid four. Concentrated liquid four is decolorized and filtered while hot. The filtrate is cooled and crystallized. Then the crystallized liquid is filtered to obtain filtrate three and filter cake three. Filter cake three is dried to obtain potassium chloride. Filtrate three is combined into the next batch of salt phase liquid for processing.

[0039] Regarding step (1):

[0040] Impurities in phytic acid-soaked corn water are effectively removed by ceramic membrane filtration.

[0041] In some embodiments of the present invention, the filtration pore size of the ceramic membrane is 40-60 nm; more preferably, it is 50 nm.

[0042] Regarding step (2):

[0043] Before electrodialysis separation, this invention first uses tartaric acid to remove metal ions from the solution, thereby ensuring the stability of electrodialysis separation and reducing the risk of membrane fouling.

[0044] In some embodiments of the present invention, the tartaric acid is 0.5-1% of the permeate volume. Under certain conditions, the tartaric acid complexes with calcium and magnesium ions in the solution to form calcium tartrate and magnesium tartrate precipitates.

[0045] When using magnesium tartrate precipitation, in addition to the amount of tartaric acid added, precipitation temperature and pH also affect the removal efficiency of calcium and magnesium ions. If the pH is too high, some protein in the solution will precipitate, thus reducing the protein yield. If the pH is too low, the solubility of calcium and magnesium tartrate increases, resulting in incomplete precipitation and affecting the separation effect of subsequent electrodialysis, thereby reducing the purity of the protein. If the temperature is too high, the protein will denature, and the solubility of calcium and magnesium tartrate will also increase, preventing complete precipitation. If the temperature is too low, refrigeration equipment is required, increasing costs, and low temperatures may lead to incomplete reaction of tartrate salts. Therefore, to effectively remove calcium and magnesium ions from the solution, this invention effectively controls the pH of the solution to 5-5.5, specifically preferably 5, 5.1, 5.2, 5.3, 5.4, or 5.5, but is not limited to these; the cooling reaction temperature is controlled at 20°C.

[0046] In some embodiments of the present invention, the cooling reaction process is as follows: the permeate is cooled to 20°C at a rate of 10°C / h, and the reaction is carried out for 2-4 hours. By effectively controlling the cooling rate and reaction time, calcium and magnesium ions in the solution are fully complexed with tartaric acid to precipitate. If the cooling rate is too low, the precipitation efficiency will be affected; if the cooling rate is too high, the reaction will be incomplete, and some calcium and magnesium ions will not be able to complex with tartaric acid to form precipitates.

[0047] Regarding step (3):

[0048] To recover lactic acid from the solution, the present invention concentrates the filtrate and then slowly cools it to allow the lactic acid to be fully extracted from the solution.

[0049] In some embodiments of the present invention, the solid content of concentrate one is 58-63 wt%. Specifically, the solid content of concentrate one is preferably 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, or 63 wt%, but is not limited thereto. The solid content will affect the purity and yield of the product to a certain extent. If the solid content is too high, some protein will precipitate along with lactic acid during subsequent cooling crystallization, which will not only affect the purity of lactic acid but also reduce the protein yield; if the solid content is too low, some lactic acid will remain in the filtrate during cooling crystallization, affecting the purity of the protein.

[0050] In some embodiments of the present invention, the cooling rate for slow cooling crystallization is 10°C / h, the crystallization temperature is 25°C, and the crystallization time is 12-24h; specifically, the crystallization time is preferably 12h, 14h, 16h, 18h, 20h, 22h, or 24h, but is not limited thereto. During this process, a cooling rate that is too fast will cause some protein to precipitate, resulting in a lower protein yield, while a cooling rate that is too slow will reduce crystallization efficiency and increase costs.

[0051] Regarding step (4):

[0052] This invention uses electrodialysis technology to separate potassium ions from filtrate two. In order to ensure a good separation effect, it is necessary to reasonably control the conditions of electrodialysis separation.

[0053] In some embodiments of the present invention, the refractive index of the diluent is 20-30, preferably 20, 22, 24, 26, 28, or 30, but is not limited thereto. If the refractive index of the diluent is too high, i.e., the solution concentration is too high, it will affect the separation effect; conversely, if the refractive index of the diluent is too low, i.e., the solution concentration is too low, it will increase the processing volume and increase processing costs.

[0054] In some embodiments of the present invention, during the electrodialysis process, in the initial stage of separation, a diluent is pumped into the desalination chamber of the electrodialysis device, water is added to the salt phase chamber, and a potassium sulfate solution or sodium sulfate solution is added to the electrode chamber, wherein the concentration of the potassium sulfate solution or sodium sulfate solution is 3-5 wt%; the fixed current during the electrodialysis process is 3.3-3.5 A.

[0055] During separation, the electrodialysis membrane uses a divalent ion separation membrane, which, under certain conditions, can effectively increase the resistance of divalent ions, thereby separating the monovalent ions from the diluent.

[0056] Regarding step (5):

[0057] In some embodiments of the present invention, the solid content of concentrate II is 50-55 wt%.

[0058] Regarding step (6):

[0059] This invention involves initially concentrating the salt phase liquid, then decolorizing it with activated carbon, and finally crystallizing it under certain conditions to recover potassium chloride from the salt phase liquid.

[0060] In some embodiments of the present invention, the solid content of concentrate three is 13 wt%, and the membrane pressure during concentration is 5-6 MPa; the solid content of concentrate four is 60 wt%.

[0061] In some embodiments of the present invention, activated carbon is added during the decolorization process. The amount of activated carbon added is 1-3‰ of four volumes of the concentrated liquid. The decolorization process is carried out at a temperature of 80°C for 2-3 hours.

[0062] In some embodiments of the present invention, during cooling crystallization, the filtrate after decolorization is cooled to 20°C at a rate of 10-15°C / h, and the crystallization process lasts for 12-20 hours.

[0063] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0064] In the following embodiments, unless otherwise specified, all raw materials are commercially available, and all conditions are conventional conditions in the art.

[0065] The yield of the target product is calculated as follows:

[0066] Lactic acid (%) = [(mass of lactic acid product × lactic acid content in lactic acid product) / (mass of corn soaking water × lactic acid content in corn soaking water)] × 100%;

[0067] Protein (%) = [(mass of protein product × protein content in protein product) / (mass of corn soaking water × protein content in corn soaking water)] × 100%;

[0068] Potassium chloride (%) = [(mass of potassium chloride product × potassium chloride content in potassium chloride product) / (mass of corn soaking water × potassium chloride content in corn soaking water)] × 100%.

[0069] Example 1

[0070] A method for efficiently recovering protein, lactic acid, and potassium chloride from dephytate corn soaking water includes the following steps:

[0071] (1) Filter 50 kg of dephytate corn soaking water (dry matter 12 wt%, protein content 6 wt%, lactic acid content 3.12 wt%, calcium 50 ppm, magnesium 2000 ppm, potassium chloride 1 wt%) using a ceramic membrane (filtration pore size 50 nm), and collect the permeate.

[0072] (2) Add tartaric acid (1% of the volume of permeate one) to permeate one, add potassium hydroxide to adjust the pH of the solution to 5, cool down to 20°C at a rate of 10°C / h, react for 4h, filter the solution after the reaction is completed, and collect filtrate one.

[0073] (3) The filtrate was concentrated to a solid content of 58 wt% to obtain concentrated liquid one. The concentrated liquid one was cooled to 25 ℃ at a cooling rate of 10 ℃ / h and crystallized for 18 h. Finally, the crystallization liquid was filtered to obtain filtrate two and filter cake two. Filter cake two was dried to obtain 1.63 kg of lactic acid with a lactic acid content of 74.1 wt% and a yield of 77.4%.

[0074] (4) Add water to the filtrate 2 to dilute it and obtain a diluted solution (refractive index 20). The diluted solution is subjected to electrodialysis. The electrodialysis membrane is a divalent ion separation membrane (Shandong Tianwei Membrane Technology Co., Ltd.). Add 0.5 BV of water to the salt phase chamber, and add a 3wt% potassium sulfate solution or sodium sulfate solution to the electrode chamber. Under the condition of a fixed current of 3.3A, the solution in the desalination chamber is treated until the conductivity of the solution in the desalination chamber is <8-9 ms / cm. Then stop the operation and collect the desalination solution and the salt phase solution.

[0075] (5) The desalination solution was concentrated to a solid content of 50 wt% to obtain concentrated solution II. Concentrated solution II was filtered by plate and frame filter to obtain clear filtrate. The clear filtrate was dried to obtain 3.44 kg of protein product with a protein content of 74.1 wt% and a yield of 85.0%.

[0076] (6) The salt phase liquid is concentrated using a reverse osmosis membrane (the membrane pressure during concentration is 5-6 MPa) to a solid content of 13 wt%, to obtain concentrate three. Concentrate three is then thermally concentrated to a solid content of 70 wt%, to obtain concentrate four. Activated carbon (3‰ of the volume of concentrate four) is added to concentrate four, and the solution is decolorized at 80°C for 3 hours. After the decolorization treatment, the solution is filtered while hot. The filtrate is cooled to 20°C at a rate of 10°C / h and crystallized for 8 hours. The crystallized solution is then filtered to obtain filtrate three and filter cake three. Filter cake three is dried to obtain 0.35 kg of potassium chloride with a potassium chloride content of 85.1 wt% and a yield of 59.6%. Filtrate three is combined with the next batch of salt phase liquid for further processing.

[0077] Example 2

[0078] A method for efficiently recovering protein, lactic acid, and potassium chloride from dephytate corn soaking water includes the following steps:

[0079] (1) Filter 50 kg of dephytate corn soaking water (dry matter 12 wt%, protein content 6 wt%, lactic acid content 3.12 wt%, calcium 50 ppm, magnesium 2000 ppm, potassium chloride 1 wt%) using a ceramic membrane (filtration pore size 50 nm), and collect the permeate.

[0080] (2) Add tartaric acid (1% of the volume of permeate one) to permeate one, add potassium hydroxide to adjust the pH of the solution to 5, cool down to 20°C at a rate of 10°C / h, react for 4h, filter the solution after the reaction is completed, and collect filtrate one.

[0081] (3) The filtrate was concentrated to a solid content of 60 wt% to obtain concentrated liquid one. Concentrated liquid one was cooled to 25 ℃ at a cooling rate of 10 ℃ / h and crystallized for 12 h. Finally, the crystallization liquid was filtered to obtain filtrate two and filter cake two. Filter cake two was dried to obtain 1.61 kg of lactic acid with a lactic acid content of 73.2 wt% and a yield of 75.5%.

[0082] (4) Add water to the second filtrate to dilute it and obtain a diluted solution (refractive index 25). The diluted solution is subjected to electrodialysis. The electrodialysis membrane is a divalent ion separation membrane (Shandong Tianwei Membrane Technology Co., Ltd.). Add 0.5 BV of water to the salt phase chamber, and add a 4 wt% potassium sulfate solution or sodium sulfate solution to the electrode chamber. Under the condition of a fixed current of 3.5 A, the solution in the desalination chamber is treated until the conductivity of the solution in the desalination chamber is <8-9 ms / cm. Then stop the operation and collect the desalination solution and the salt phase solution.

[0083] (5) The desalination solution was concentrated to a solid content of 53 wt% to obtain concentrated solution II. Concentrated solution II was filtered by plate and frame filter to obtain clear filtrate. The clear filtrate was dried to obtain 3.42 kg of protein product with a protein content of 73.3 wt% and a yield of 83.6%.

[0084] (6) The salt phase liquid is concentrated using a reverse osmosis membrane (the membrane pressure during concentration is 5-6 MPa) to a solid content of 13 wt%, to obtain concentrate three. Concentrate three is then thermally concentrated to a solid content of 65 wt%, to obtain concentrate four. Activated carbon (2‰ of the volume of concentrate four) is added to concentrate four, and the solution is decolorized at 80°C for 3 hours. After the decolorization treatment, the solution is filtered while hot. The filtrate is cooled to 20°C at a rate of 15°C / h and crystallized for 10 hours. The crystallized solution is then filtered to obtain filtrate three and filter cake three. Filter cake three is dried to obtain 0.34 kg of potassium chloride with a potassium chloride content of 82.3 wt% and a yield of 56.0%. Filtrate three is combined with the next batch of salt phase liquid for further processing.

[0085] Example 3

[0086] A method for efficiently recovering protein, lactic acid, and potassium chloride from dephytate corn soaking water includes the following steps:

[0087] (1) Filter 50 kg of dephytate corn soaking water (dry matter 12 wt%, protein content 6 wt%, lactic acid content 3.12 wt%, calcium 50 ppm, magnesium 2000 ppm, potassium chloride 1 wt%) using a ceramic membrane (filtration pore size 50 nm), and collect the permeate.

[0088] (2) Add tartaric acid (0.5% of the volume of permeate one) to permeate one, add potassium hydroxide to adjust the pH of the solution to 5.5, cool down to 20℃ at a rate of 10℃ / h, react for 2h, filter the solution after the reaction is completed, and collect filtrate one.

[0089] (3) The filtrate was concentrated to a solid content of 63wt% to obtain concentrated liquid one. The concentrated liquid one was cooled to 25℃ at a cooling rate of 10℃ / h and crystallized for 18h. Finally, the crystallization liquid was filtered to obtain filtrate two and filter cake two. Filter cake two was dried to obtain 1.59kg of lactic acid with a lactic acid content of 71.8wt% and a yield of 73.2%.

[0090] (4) Add water to the second filtrate to dilute it and obtain a diluted solution (refractive index 30). The diluted solution is subjected to electrodialysis. The electrodialysis membrane is a divalent ion separation membrane (Shandong Tianwei Membrane Technology Co., Ltd.). Add 0.5 BV of water to the salt phase chamber, and add a 5 wt% potassium sulfate solution or sodium sulfate solution to the electrode chamber. Under the condition of a fixed current of 3.3 A, the solution in the desalination chamber is treated until the conductivity of the solution in the desalination chamber is <8-9 ms / cm. Then stop the operation and collect the desalination solution and the salt phase solution.

[0091] (5) Concentrate the desalination solution to a solid content of 55wt% to obtain concentrated solution two. Filter concentrated solution two with a plate and frame filter to obtain clear filtrate. Dry the clear filtrate to obtain 3.45kg of protein product with a protein content of 72wt%.

[0092] (6) The salt phase liquid is concentrated using a reverse osmosis membrane (the membrane pressure during concentration is 5-6 MPa) to a solid content of 13 wt%, to obtain concentrate three. Concentrate three is then thermally concentrated to a solid content of 60 wt%, to obtain concentrate four. Activated carbon (1‰ of the volume of concentrate four) is added to concentrate four, and the solution is decolorized at 80°C for 2 hours. After the decolorization treatment, the solution is filtered while hot. The filtrate is cooled to 20°C at a rate of 10°C / h and crystallized for 12 hours. The crystallized solution is then filtered to obtain filtrate three and filter cake three. Filter cake three is dried to obtain 0.33 kg of potassium chloride with a potassium chloride content of 84 wt% and a yield of 55.4%. Filtrate three is combined with the next batch of salt phase liquid for further treatment.

[0093] Example 4

[0094] A method for efficiently recovering protein, lactic acid, and potassium chloride from dephytate corn soaking water includes the following steps:

[0095] (1) Filter 50 kg of dephytate corn soaking water (dry matter 12 wt%, protein content 6 wt%, lactic acid content 3.12 wt%, calcium 50 ppm, magnesium 2000 ppm, potassium chloride 1 wt%) using a ceramic membrane (filtration pore size 50 nm), and collect the permeate.

[0096] (2) Add tartaric acid (0.5% of the volume of permeate one) to permeate one, add potassium hydroxide to adjust the pH of the solution to 5.5, cool down to 20℃ at a rate of 10℃ / h, react for 2h, filter the solution after the reaction is completed, and collect filtrate one.

[0097] (3) The filtrate was concentrated to a solid content of 58 wt% to obtain concentrated liquid one. The concentrated liquid one was cooled to 25 ℃ at a cooling rate of 10 ℃ / h and crystallized for 24 h. Finally, the crystallization liquid was filtered to obtain filtrate two and filter cake two. Filter cake two was dried to obtain 1.58 kg of lactic acid with a lactic acid content of 72.6 wt% and a yield of 73.5%.

[0098] (4) Add water to the filtrate 2 to dilute it and obtain a diluted solution (refractive index 20). The diluted solution is subjected to electrodialysis. The electrodialysis membrane is a divalent ion separation membrane (Shandong Tianwei Membrane Technology Co., Ltd.). Add 0.5 BV of water to the salt phase chamber, and add a 3wt% potassium sulfate solution or sodium sulfate solution to the electrode chamber. Under the condition of a fixed current of 3.5A, the solution in the desalination chamber is treated until the conductivity of the solution in the desalination chamber is <8-9 ms / cm. Then stop the operation and collect the desalination solution and the salt phase solution.

[0099] (5) The desalination solution was concentrated to a solid content of 50 wt% to obtain concentrated solution II. Concentrated solution II was filtered by plate and frame filter to obtain clear filtrate. The clear filtrate was dried to obtain 3.38 kg of protein product with a protein content of 73.5 wt% and a yield of 82.8%.

[0100] (6) The salt phase liquid is concentrated using a reverse osmosis membrane (the membrane pressure during concentration is 5-6 MPa) to a solid content of 13 wt%, to obtain concentrate three. Concentrate three is then thermally concentrated to a solid content of 65 wt%, to obtain concentrate four. Activated carbon (3‰ of the volume of concentrate four) is added to concentrate four, and the solution is decolorized at 80°C for 2 hours. After the decolorization treatment, the solution is filtered while hot. The filtrate is cooled to 20°C at a rate of 15°C / h and crystallized for 14 hours. The crystallized solution is then filtered to obtain filtrate three and filter cake three. Filter cake three is dried to obtain 0.34 kg of potassium chloride with a potassium chloride content of 83.5 wt% and a yield of 56.8%. Filtrate three is combined with the next batch of salt phase liquid for further processing.

[0101] To verify the effectiveness of the present invention, Example 4 is used as a reference, and further explanation is provided below in conjunction with several comparative examples.

[0102] Comparative Example 1

[0103] Compared with Example 1, the difference is that in step (2), potassium hydroxide was added to adjust the pH of the solution to 4, and other conditions were the same as in Example 1; 1.38 kg of lactic acid was obtained, with a lactic acid content of 68 wt% and a yield of 60.2%; 3.2 kg of protein product was obtained, with a protein content of 68 wt% and a yield of 72.5 wt%; 0.34 kg of potassium chloride was obtained, with a potassium chloride content of 78 wt% and a yield of 53.0%.

[0104] Comparative Example 2

[0105] Compared with Example 1, the difference is that in step (2), potassium hydroxide was added to adjust the pH of the solution to 6.5, and other conditions were the same as in Example 1; 1.73 kg of lactic acid was obtained, with a lactic acid content of 65.2 wt% and a yield of 72.3%; 2.98 kg of protein product was obtained, with a protein content of 72 wt% and a yield of 71.5%; and 0.29 kg of potassium chloride was obtained, with a potassium chloride content of 73.1 wt% and a yield of 42.4%.

[0106] Comparative Example 4

[0107] Compared with Example 1, the difference is that in step (2), the temperature is lowered first and then tartaric acid and potassium hydroxide are added, while other conditions are the same as in Example 1; 1.62 kg of lactic acid is obtained, with a lactic acid content of 62 wt% and a yield of 64.4%; 2.8 kg of protein product is obtained, with a protein content of 65.1 wt% and a yield of 60.8%; 0.23 kg of potassium chloride is obtained, with a potassium chloride content of 76.2 wt% and a yield of 35.1%.

[0108] Comparative Example 5

[0109] Compared with Example 1, the difference is that in step (3), the solid content of concentrate one is 50 wt%, and other conditions are the same as in Example 1; 0.9 kg of lactic acid is obtained, with a lactic acid content of 73.2 wt% and a yield of 42.2%; 3.62 kg of protein product is obtained, with a protein content of 62 wt% and a yield of 74.8%; 0.32 kg of potassium chloride is obtained, with a potassium chloride content of 78.8 wt% and a yield of 50.4%.

[0110] Comparative Example 6

[0111] Compared with Example 1, the difference is that in step (3), the solid content of concentrate one is 70 wt%, and other conditions are the same as in Example 1; 2.1 kg of lactic acid is obtained, with a lactic acid content of 61 wt% and a yield of 82.1%; 2.66 kg of protein product is obtained, with a protein content of 69.2 wt% and a yield of 61.4%; 0.33 kg of potassium chloride is obtained, with a potassium chloride content of 76 wt% and a yield of 50.2%.

[0112] Comparative Example 7

[0113] Compared with Example 1, the difference is that in step (3), the cooling rate is 20℃ / h, and other conditions are the same as in Example 1; 1.65kg of lactic acid is obtained, with a lactic acid content of 68wt% and a yield of 71.9%; 3.1kg of protein product is obtained, with a protein content of 69.1wt% and a yield of 71.4%; 0.33kg of potassium chloride is obtained, with a potassium chloride content of 80wt% and a yield of 52.8%.

[0114] Comparative Example 8

[0115] Compared with Example 1, the difference is that in step (4), the refractive index of the diluent is 40, and other conditions are the same as in Example 1; 1.59 kg of lactic acid is obtained, with a lactic acid content of 73.2 wt% and a yield of 74.6%; 3.1 kg of protein product is obtained, with a protein content of 62 wt% and a yield of 64.1%; 0.21 kg of potassium chloride is obtained, with a potassium chloride content of 72 wt% and a yield of 30.2%.

[0116] Comparative Example 9

[0117] Compared with Example 1, the difference is that in step (4), the current is fixed at 2.0A, and other conditions are the same as in Example 1; 1.58kg of lactic acid is obtained, with a lactic acid content of 72.9wt% and a yield of 73.8%; 2.9kg of protein product is obtained, with a protein content of 67wt% and a yield of 64.8%; 0.1kg of potassium chloride is obtained, with a potassium chloride content of 68wt% and a yield of 13.6%.

[0118] Comparative Example 10

[0119] Compared with Example 1, the difference is that in step (4), the current is fixed at 4.5A, and other conditions are the same as in Example 1; 1.64 kg of lactic acid is obtained, with a lactic acid content of 73.3 wt% and a yield of 77.1%; 2.94 kg of protein product is obtained, with a protein content of 68 wt% and a yield of 66.6%; 0.12 kg of potassium chloride is obtained, with a potassium chloride content of 71 wt% and a yield of 17.0%.

[0120] Comparative Example 11

[0121] Compared with Example 1, the difference is that in step (6), the solid content of concentrate four is 50 wt%, and other conditions are the same as in Example 1; 1.53 kg of lactic acid is obtained, with a lactic acid content of 72.8 wt% and a yield of 71.4%; 3.4 kg of protein product is obtained, with a protein content of 72.1 wt% and a yield of 81.7%; 0.09 kg of potassium chloride is obtained, with a potassium chloride content of 81.2 wt% and a yield of 14.6%.

[0122] In summary, compared with the comparative example, the present invention removes calcium and magnesium ions from the phytic acid solution under certain conditions, then crystallizes it under certain conditions to recover lactic acid; it uses electrodialysis to separate potassium chloride and protein from the solution, and finally recovers the protein and potassium chloride under certain conditions.

[0123] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely to aid in understanding the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for efficiently recovering protein, lactic acid, and potassium chloride from dephytized corn soaking water, characterized in that, Includes the following steps: (1) Use a ceramic membrane with a pore size of 40-60nm to filter the corn soaking water to remove phytic acid and collect the permeate. (2) Add tartaric acid to permeate solution one, adjust the pH of the solution to 5-5.5, cool down the reaction, filter the solution after the reaction is completed, and collect filtrate one; the tartaric acid is 0.5-1% of the volume of permeate solution one; potassium hydroxide is used to adjust the pH of permeate solution one; (3) Concentrate the filtrate to obtain concentrate one. Slowly cool the concentrate one and crystallize it. Finally, filter the crystallization liquid to obtain filtrate two and filter cake two. Dry the filter cake two to obtain lactic acid. The solid content of concentrate one is 58-63wt%. The slow cooling process is to cool to 25℃ at a cooling rate of 10℃ / h and crystallize for 12-24h. (4) Add water to the second filtrate to dilute it and obtain a diluted solution. Perform electrodialysis on the diluted solution. The electrodialysis membrane is a divalent ion separation membrane. The treatment is carried out until the conductivity of the solution in the desalination chamber is <8-9 ms / cm. Stop the operation and collect the desalination solution and the salt phase solution. The refractive index of the diluted solution is 20-30. During the electrodialysis treatment, water is added to the salt phase chamber and one of potassium sulfate solution and sodium sulfate solution is added to the electrode chamber. The concentration of the potassium sulfate solution and sodium sulfate solution is 3-5 wt%. The fixed current during the electrodialysis treatment is 3.3-3.5 A. (5) Concentrate the desalination solution to obtain concentrated solution II, and finally dry it to obtain the protein product; (6) The salt phase liquid is concentrated by reverse osmosis membrane to obtain concentrated liquid three. Concentrated liquid three is heated to obtain concentrated liquid four. Concentrated liquid four is decolorized and filtered while hot. The filtrate is cooled and crystallized. Then the crystallized liquid is filtered to obtain filtrate three and filter cake three. Filter cake three is dried to obtain potassium chloride. Filtrate three is combined into the next batch of salt phase liquid for processing.

2. The method for efficiently recovering protein, lactic acid, and potassium chloride from dephytized corn soaking water according to claim 1, characterized in that, In step (2), the cooling reaction process involves cooling the permeate liquid to 20°C at a rate of 10°C / h and reacting for 2-4 hours.

3. The method for efficiently recovering protein, lactic acid, and potassium chloride from dephytized corn soaking water according to claim 1, characterized in that, In step (5), the solid content of concentrate II is 50-55 wt%.

4. The method for efficiently recovering protein, lactic acid, and potassium chloride from dephytized corn soaking water according to claim 1, characterized in that, In step (6), the solid content of the concentrate three is 13wt%, and the pressure of the membrane during concentration is 5-6MPa; the solid content of the concentrate four is 60wt%.

5. The method for efficiently recovering protein, lactic acid, and potassium chloride from dephytized corn soaking water according to claim 1, characterized in that, In step (6), activated carbon is added during the decolorization process. The amount of activated carbon added is 1-3‰ of four volumes of the concentrated liquid. The decolorization temperature is 80℃ and the time is 2-3h.

6. The method for efficiently recovering protein, lactic acid, and potassium chloride from dephytized corn soaking water according to claim 1, characterized in that, In step (6), the specific process of cooling and crystallization is as follows: the filtrate after decolorization is cooled to 20°C at a rate of 10-15°C / h and crystallized for 12-20h.